<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    a{
      /*块级元素才有宽度和高度的设置*/
      width: 300px;
      height: 200px ;
      background-color: red;
      display: block;
    }
    div{
      /*行级元素不能设置高度和宽度*/
      width: 300px;
      height: 200px ;
      background-color: aqua;
      display: inline;
    }
    span{
      width: 300px;
      height: 200px ;
      background-color: aqua;
      display: inline-block;
    }
  </style>
</head>
<body>
<a href="https:/www.baidu.com">百度</a>
<div>块级元素</div>
<div>块级元素</div>
<span>行内元素转化成行内块元素</span>
</body>
</html>